These Birds Have Sung the Same Songs for 1,000 Years

The swamp sparrow’s impressively preserved repertoire suggests that birds, like humans, have the ability to sustain culture through the centuries.

We humans may pride ourselves on having some unique traits among animals, such as the ability to teach our traditions, habits and ways of living to our children and preserve them over generations. But it turns out we aren’t the only ones in the animal kingdom with this ability.

A new study of American swamp sparrows suggests that these little birds have been singing the same songs for up to 1,000 years, creating and preserving song traditions that rival even the longest-lasting human cultural traditions.

In the new study, published in Nature Communications, researchers at Queen Mary University of London, Imperial College London and Duke University recorded the song repertoires of 615 birds in six different populations of swamp sparrows (Melospiza georgiana) from four different states: New York, Pennsylvania, Michigan and Wisconsin. The species is common to the marshes and wetlands of the northeastern and central United States.

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After recording the songs, the scientists used computer software to analyze the diversity of the different tunes. They eventually picked out 160 different song types, and created a mathematical model to map how the different song types spread within groups of swamp sparrows over time.

What they found was that though young birds hear a lot of different song types, they do not pick the ones they learn at random, but choose ones that are more common. This learning strategy, known as conformist bias, was previously thought to be exclusive to humans. As a result, new birdsong types get filtered out almost immediately, leaving the same old tunes behind, and creating some remarkably stable traditions.

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The researchers also found that young sparrows learn the songs with surprising accuracy. They estimated that the birds correctly imitate the songs they attempt to learn 98 percent of the time.

Scientists have long since debunked the myth that “bird-brained” is an insult, finding that birds’ tiny brains are packed more densely with neurons than those of many other animals, allowing for the advanced and complex cognition that we observe in crows, ravens and parrots, among other particularly smart bird species. The new study lends weight to this effort, showing that swamp sparrows preserve their song traditions over centuries through selection, imitation and learning.

“The longstanding stable traditions so characteristic of human behavior have often been ascribed to the high cognitive abilities of humans and our ancestors,” study co-author Stephen Nowicki, professor of biology at Duke, told Phys.org. “But what we’re showing is that a relatively simple set of rules that these songbirds are capable of following can achieve equally lasting traditions.”